The ink fountain is crucial to consistency and productivity, especially for longer runs. While it’s possible to add ink manually as needed on shorter jobs, beyond a certain point it’s quicker to set up the fountain so you don’t have to stop the press to run around and add ink. Once set up the fountain also helps maintain consistency throughout the run, and the longer the run, the more this pays off. Of course, the heavier the coverage, the more essential the fountain becomes.
The fountain controls both the overall amount of inking, and the location at which it’s added. The windmill has twelve fountain keys to span the width of the printable area. As the oscillating distributor roller cannot be dialed out of action (as on the Heidelberg cylinder for example), the ink doesn’t stay strictly in line with the fountain keys. In other words, you can’t have heavy inking at key 6 and light inking at 4 and 5. The ink will work its way sideways as the press runs.
When I set up the fountain I usually leave out the ductor roller until setup is complete. First I set the advance control to “8” so changes at the fountain keys are seen as quickly as possible, then begin opening up the keys in line with the artwork to be printed. I try to set the ink level so an advance setting around 4 or 5 results in the correct ink amount. This leaves the most room in either direction to change the amount of advance as needed.
Especially with lighter colors, it’s important to not tighten down any of the fountain keys too much. A very tight setting will actually scrape off a bit of metal over the run, which can turn the ink grayish.
The fountain can also be used to take off ink, as when switching from a heavy form back to one with a small amount of text. If you tighten down the keys and crank the advance up to 8, the ink will be pulled from the ductor roller back into the fountain as the press runs. The ink will always transfer from the more heavily inked roller to the “drier” roller.